The purpose of this project is to investigate the short- and long-term neurobehavioral effects of methadone maintenance during pregnancy on the fetus, neonate and young child. In addition, the disposition of methadone in the mother during pregnancy and postpartum period and in the newborn will be investigated to determine if any cause and effect relationships are present. At present, we have enrolled 51 mothers (42/48 have delivered) on methadone-maintenance, and 22 control mothers and their infants. The methadone mothers are closely followed prenatally and bloods and urines collected for methadone disposition. After delivery, both control and methadone infants are followed every two months for the first year and then every 3 months for two years. During these visits they receive a physical examination and necessary immunizations, neurological and developmental evaluations, as well as behavioral testing which includes visual and auditory habituation, Bayley Scales, object permanence and mother-infant interaction. The oldest child in the study is now 18 months. Data has been analyzed for the first 6 months of life. The significant findings are: 1) Brazelton's neurobehavioral evaluation at birth showed that the methadone babies were more tremulous, irritable, hypertonic, and less alert and hard to console than controls. Hypertonicity and irritability and tremulousness was present in many at 2 and 4 months, but by 6 months there were no significant differences in neurological evaluations between the two groups. As far as the rate of growth and development and incidence of infections, there were no differences. Behavioral evaluations revealed no significant differences in Bayleys or auditory habituations.